Four charged particle final states in untagged two-photon events at PEP

Untagged two photon events with four charged particles in the final state have been examined using the PEP4-TPC detector facility at the PEP positron-electron storage ring in the Stanford Linear Accelerator Center. A total e+ eπ integrated luminosity of 60.3 pb-1 at 29 GeV/c2 per beam was recorded. The dE/dx measurement capability of the Time Project Chamber (TPC) has been used to identify particles of 87% of 4π steradians. In γγ → π+ π- π+ π- events the fractions of rho0 rho0, rho 0 π+ π-, and π+ π- π+ π- from phase space production were measured. A large rho0 rho0 cross-section at threshold was seen in agreement with results found elsewhere. Angular distributions of rho0 rho0 production showed no 2- contribution and showed consistency with isotropic production and decay. In γγ → K+ K- π+ π- events the total cross-section was measured and angular distributions compared to isotropic production and decay. The production of γγ → K0 K+ π- and γγ → phi π+ π- has been observed. An upper limit on γγ → K*0 K*0 production of 13 nb was measured